Reactivity 3.2 Electron transfer reactions (HL)
Reactivity 3.2.12
Understandings:
  • The hydrogen half-cell H2(g) ⇌ 2H+(aq) + 2e– is assigned a standard electrode potential of zero by convention. It is used in the measurement of standard electrode potential, E⦵.
Learning outcomes:
  • Interpret standard electrode potential data in terms of ease of oxidation/reduction.
Additional notes:
  • Standard electrode potentials are given in the data booklet.​
This video covers standard electrode potentials and the hydrogen half-cell. 
Note that the IB now uses the term hydrogen half-cell instead of SHE (standard hydrogen electrode).
Reactivity 3.2.13
Understandings:
  • Standard cell potential, E⦵  , can be calculated from standard potentials.  E⦵ has a positive value for a spontaneous 
Learning outcomes:
  • Predict whether a reaction is spontaneous in the forward or reverse direction from E⦵.​
This video covers how to calculate the cell potential. 
Reactivity 3.2.14
Understandings:
  • The equation ΔG⦵ = − nFE⦵  shows the relationship between standard cell change in Gibbs energy and standard electrode potential for a reaction.
Learning outcomes:
  • Determine the value for ΔG⦵ from E⦵ data.
Additional notes:
  • The equation and the value of F in C mol–1 are given in the data booklet.
Linking questions:
  • Reactivity 1.4 How can thermodynamic data also be used to predict the spontaneity of a reaction?
This video covers how to calculate ΔG for a voltaic cell. 
Reactivity 3.2.15
Understandings:
  • During electrolysis of aqueous solutions, competing reactions can occur at the anode and cathode, including the oxidation and reduction of water.
Learning outcomes:
  • Deduce from standard electrode potentials the products of the electrolysis of aqueous solutions.
Additional notes:
  • Electrolytic processes should include the electrolysis of water and of aqueous solutions.​
This video covers electrolysis of aqueous solutions. 
Reactivity 3.2.16
Understandings:
  • Electroplating involves the electrolytic coating of an object with a metallic thin layer.
Learning outcomes:
  • Deduce equations for the electrode reactions during electroplating.​
This video covers electroplating.